console.log('start')
var p = new Promise((resolve) => {
  console.log('promise')
  resolve('123')
})
p.then((arg) => { console.log(arg) })
var pp = p.then((arg) => {
  console.log(arg)
  console.log('then1')
  var p1 = new Promise((resolve) => resolve())
  return p1
})
pp.then(() => { console.log('pp then1') })

// p.then(() => { console.log('then2') })
console.log('end')
